Confocal scanner system and method

ABSTRACT

A radiation image that has been stored in an image plate ( 19 ), such as a photostimulable phosphor screen is read by stimulating an information-bearing target area ( 13 ) with stimulating light ( 1 ). The information bearing target area responds to this stimulation by emitting information-bearing light ( 2 ) and reflecting backscatter light ( 3 ). The combination ( 4 ) of information-bearing light and backscatter light is collimated, allowing efficient rejection of backscatter light. The information-bearing light is subsequently focused onto an information receiving target ( 17 ), such as a charge-coupled device (CCD).

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 10/947,082,filed on Sep. 22, 2004, entitled “Confocal Scanner System and Method”,which application is based on U.S. Provisional Application Ser. No.60/504,878 entitled “Confolcal Scanner”, filed on Sep. 22, 2003, theteachings of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to radiation image recording systems wherein aradiation image is recorded on a photostimulable phosphor screen.

2. Background Art

Any discussion of the prior art throughout the specification should inno way be considered as an admission that such prior art is widely knownor forms part of common general knowledge in the field.

A recorded image, such as an X-ray, can be reproduced by stimulating anexposed photostimulable phosphor screen by means of stimulatingradiation and by detecting the light that is emitted by the phosphorscreen upon stimulation and converting the detected light into anelectrical signal representation of the radiation image. There exists inthe prior art various scanners for use in reading an image from astimulable phosphor plate; for example Exelmans (U.S. Pat. No.5,548,126) describes a scanner for use in a digital radiography system.As discussed in Exelmans, a certain type of phosphor can be energized toan excited state by exposure to X-rays, and then can be stimulated byvisible or infrared light (i.e. light of a first sense) to emit visiblelight in the blue region of the spectrum (i.e. light of a second sense).Other separate senses of light such as polarization state can be used inlieu of wavelength to discriminate between stimulation and emissionlight.

Typically, light emitted by the phosphor screen upon stimulation isdetected by means of an array of charge coupled devices. The light,which is used for stimulating the phosphor screen, has to be separatedfrom the light emitted by the screen upon stimulation.

In order to capture the image stored within the phosphor, one mustcapture the light of the second sense without contaminating it withbackscatter light of the first sense. One possible way to avoid suchcontamination is to use the decay-time of the phosphor to discriminate,via gating, between the two light senses described above. However, asdiscussed in Leblens (U.S. Pat. No. 6,228,286), reliance on decay-time,can limit the throughput of digital radiography system.

One issue with a wavelength based system is the need to maximizesignal-to-noise ratio (S/N), and therefore requiring the rejection, suchas by filtering, of backscatter light in the stimulation wavelength bandwhile maximizing the amount of light captured in the desired emissionwavelength band. For example, Struye (U.S. Pat. No. 6,495,850) statesthat the optical density of the filter at the stimulation wavelengthrange should be at least 8 while the transmission at the emissionwavelength should be higher than 75%. Therefore, there is a tendency, inthe prior art, to separate the stimulation and emission wavelength bandsto accommodate such characteristics as the filter roll-off.

While this helps in discrimination, it complicates the optical systemdue to dispersion effects, such effects are discussed in Modern OpticalEngineering, W. J. Smith, ISBN 0-07-136360-2. In an optical scanner,such as described in the specification below, such dispersion effectscan result in uneven stimulation of an information bearing target areaof the image plate and a reduction in quality of the informationtransferred from the image plate to an optical sensor. Struye furtherteaches that in order to maximize collection efficiency for an imagescanner a large solid angle of the emission must be captured. However,allowing such a large solid angle to pass through an optical filterrequires the use of absorptive rather than thin film coated filters,which poses significant materials challenges in meeting the emissionwavelength transmission of 75% while rejecting the stimulatingwavelengths at very high optical densities.

There exists a need for a scanning system for radiation image recordingsystems that can high provide a high collection efficiency of theemission wavelengths while rejecting a high degree of the stimulatingwavelength.

SUMMARY OF THE INVENTION

The following summary of the invention is provided to facilitate anunderstanding of some of the innovative features unique to the presentinvention. A full appreciation of the various aspects of the inventioncan only be gained by taking the entire specification, claims, drawings,and abstract as a whole.

The present invention describes a system and method to provide a compactsystem for reading a radiation image that has been stored in aphotostimulable phosphor screen wherein stimulation light and lightemitted by the screen upon stimulation are optically separated. Thepresent invention avoids undesirable optical dispersion effects byavoiding passing both the initial stimulation wavelengths and resultantemission wavelengths through a common refractive element having opticalpower, such as an imaging lens. To maintain high collection efficiencyand a high degree of discrimination, the present invention utilizes aconfocal optical arrangement, which can encompass a series of filterswithin the collimated space of this confocal arrangement.

According to a first aspect, the present invention is realized by aradiation information recording system comprising

-   -   a source of light of a first sense,    -   an information bearing target which receives the light of the        first sense and in response thereto emits information bearing        light of a second sense together with back scatter light of the        first sense, wherein the light of the first sense and the        information bearing light do not pass through a common        reflective element having optical power,    -   means for collimating the information bearing light of the        second sense and the back scatter light of the first sense,    -   means for separating the information bearing light of the second        sense and the back scatter light of the first sense from the        collimated light,    -   an information receiving target, and    -   means for focusing the separated information bearing light onto        the information-receiving target.

According to a second aspect, the present invention is realized by amethod for using stimulating light to stimulate an information bearingtarget area into releasing information bearing light and transferringthe information bearing light to an information receiving target,wherein the initial stimulating light and the resultantinformation-bearing light do not pass through a common refractiveelement having optical power, the method comprising the steps of

-   -   receiving stimulating light of a first sense from a light        source,    -   illuminating the information bearing target area with        stimulating light, the illumination occurring about the normal        of an image aperture coincident with a portion of the        information-bearing target area,    -   receiving a combination of information bearing light of a second        sense emitted from the information bearing target area in        response to the illumination and backscatter light of the first        sense reflected from the information-bearing target,        -   the information bearing light being of a second sense, and        -   the reception also occurring about the normal of the            aperture,    -   collimating the combination of information bearing light and        backscatter light to form a collimated combined light,    -   rejecting, in collimated space, the backscatter light portion        from the collimated combined light,    -   recovering the information-bearing light, and    -   transferring the information bearing light to the information        receiving target.

Further advantages and embodiments of the present invention will becomeapparent from the following description and drawings.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying figures further illustrate the present invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 shows a confocal scanner apparatus employing dual parabolicreflectors in accordance with one illustrative embodiment of myinvention.

FIG. 2 shows additional detail for an aperture element of FIG. 1.

FIG. 3 illustrates a method of scanning a target using the apparatus ofFIGS. 1 and 2.

FIG. 4 shows a confocal scanner apparatus employing an aperturedcollimating lens and an apertured cold mirror in accordance with asecond illustrative embodiment of my invention.

FIG. 5 shows a confocal scanner apparatus employing an aperturedcollimating lens and dual coated prisms in accordance with a thirdillustrative embodiment of my invention.

FIG. 6 illustrates additional detail for the dual coated prisms of FIGS.5 and 7.

FIG. 7 shows a confocal scanner apparatus employing tapered non-imagingoptics and dual coated prisms in accordance with a fourth illustrativeembodiment of my invention.

LIST OF REFERENCE NUMBERS FOR THE MAJOR ELEMENTS IN THE DRAWING

The following is a list of the major elements in the drawings innumerical order.

-   -   1 stimulating light (of a first sense)    -   2 information bearing light (of a second sense)    -   3 backscatter light portion (of a first sense)    -   4 collimated combined light (contains both backscatter and        target light)    -   5 collimated information bearing light (contains substantially        only target light)    -   6 focused information-bearing light    -   11 light source (of stimulating light 1)    -   12 first parabolic reflector    -   13 information bearing target area    -   14 first beam-splitter    -   15 second beam-splitter    -   16 second parabolic reflector    -   17 information receiving target    -   19 image plate (e.g. photostimulable phosphor screen)    -   20 image aperture    -   21 normal to aperture (dashed line)    -   22 apertured collimating lens    -   23 first aperture (in collimating lens 22)    -   24 apertured first cold mirror    -   25 hot mirror    -   26 focusing lens    -   27 first cold mirror    -   30 second aperture (in second cold mirror 24)    -   31 coated lower prism    -   32 first hot mirror coating (lower prism 31)    -   41 coated upper prism    -   42 second hot mirror coating (upper prism 41)    -   43 third hot mirror coating (upper prism 41)    -   51 first tapered non-imaging optic    -   52 second tapered non-imaging optic    -   53 third tapered non-imaging optic    -   110 step of receiving stimulating light    -   120 step of illuminating information bearing target    -   130 step of receiving information bearing light (from target)    -   140 step of collimating information-bearing and backscatter        light    -   150 step of rejecting backscatter portion of light emitted from        target    -   160 step of recovering information-bearing light    -   170 step of transferring information bearing light to receiving        target (without passing through refractive element)

DESCRIPTION OF THE INVENTION

The present invention is designed for use with an X-ray scanner orsimilar device that modifies a image by subjecting that image plate toradiation wherein the modified image plate contains information that canbe released by the application of stimulating light.

The following descriptions are intended to demonstrate the basicprincipal of operation of the present invention. As such, additionaloptical elements, such as relay lenses, may be used to further enhanceimage quality. Such elements are also discussed in Modern OpticalEngineering and can be designed by one skilled in the art by usingoptical imaging analysis tools such as Code V from Optical ResearchAssociates (Pasadena, Calif.).

Referring first to FIG. 1, an illustrative all-reflective imagingapparatus suitable for my inventive method is shown. Stimulating light 1of a first sense, such as red light, from a light source 11 strikes afirst beam-splitter 14 which is configured to pass light of this firstsense and reflect light of a second sense, such as blue light. In oneillustrative embodiment of my invention, the beam-splitter 14 is adichroic beam-splitter. After the stimulating light 1 passes throughbeam-splitter 14, it is reflected from a first parabolic reflector 12through an image aperture 20 into an information-bearing target area 13,such as a pixel area on an image plate 19, where image plate 19 ispreferably a photostimulable phosphor screen.

The information-bearing target area 13 responds to illumination by thestimulating light 1 by emitting information-bearing light 2 of thesecond sense, such as by fluorescing blue light. The information-bearingtarget 13 also reflects a portion of the stimulating light 1 asback-scatter light 3 of the first sense, where this backscatter light 3is mixed with the information-bearing light 2 as a combination whichpasses back through image aperture 20. The combination ofinformation-bearing light 2 and backscatter light 3 reflects from firstparabolic reflector 12 as collimated combined light 4. Collimatedcombined light 4 strikes first beam splitter 14 where a portion of thebackscatter light 3 is separated from collimated combined light 4 ascollimated combined light 4 is reflected from first beam-splitter 14 anddirected toward second beam-splitter 15. Beam splitters 14 and 15 cancomprise a dichroic mirror, such as those that may be available fromOmega Optical (Brattleboro, Vt.).

Collimated combined light 4 then strikes second beam splitter 15 wheresubstantially all of the remaining backscatter light 3 is separated fromcollimated combined light 4, resulting in collimated information bearinglight 5 that contains substantially only target light being reflectedfrom second beam-splitter 15.

Collimated information bearing light 5 is then directed toward secondparabolic reflector 16. Backscatter light 3, from said beam splitters 14and 15, is preferably directed towards a blackened surface (not shown).Such surfaces are discussed in Black Surfaces for Optical Systems,Chapter 37, Handbook of Optics, ISBN 0-07-047974-7.

A first essential feature of my invention is that the combination ofinformation-bearing light 2 and backscatter light 3 is collimated beforethe information-bearing light 2 is separated from backscatter light 3 incollimated space, advantageously enabling better performance of the beamsplitters 14 and 15 as compared to the prior art, where a similarseparation is performed in non-collimated space. One illustrativeembodiment showing the separation of the information bearing light 2from backscatter light 3 in collimated space has been described above.

Focused information bearing light 6 is recovered from collimatedinformation bearing light 5 by the reflecting and focusing action ofsecond parabolic reflector 16, where this focused information-bearinglight 6 is directed to information receiving target 17, such as acharge-coupled device (CCD).

A second essential feature of my invention is that the initialstimulating light 1 and the information-bearing light 2 do not passthrough a common refractive element having optical power. For example inthe all-reflective illustrative embodiment shown above, the stimulatinglight 1 and the information-bearing light 2 commonly interact with firstbeam-splitter 14, first parabolic reflector 12 and image aperture 20,where none of these elements are refractive optical elements havingoptical power.

Referring now to FIG. 2 which illustrates additional detail of the imageaperture element 20 shown in FIG. 1. As described previously,stimulating light 1 passes through image aperture 20, illuminatinginformation-bearing target area 13 of image plate 19. As shown in FIG.2, such illumination occurs about the normal 21 of the image aperture20, where the image aperture 20 is coincident with theinformation-bearing target area 13. Note that such apertures are knownin the art to maximize image quality, and apertures that may be suitablefor use with the present invention may be available from Lenox Laser(Glen Arm, Md.).

In one preferred embodiment, image aperture has knife-edges in order tominimize unwanted reflections internal to the aperture. It is alsoadvantageous to place the sharp edged hole as close as practical toinformation-bearing target area 13 thereby maximizing rejection ofunwanted backscatter and information-bearing off-axis light from areassurrounding information-bearing target 13.

Also, as described previously, the information bearing target area 13responds to the stimulating light 1 by emitting information-bearinglight 2 and reflecting backscatter light 3. As shown in FIG. 2, suchemission and reflection also occurs about the normal 21 of the imageaperture 20, where the image aperture 20 is centered on theinformation-bearing target area 13.

Referring now to FIG. 3 and describing the inventive method steps of oneembodiment of my invention in view of the illustrative apparatus ofFIGS. 1 and 2. Stimulating light 1 of a first sense, such as red light,is received (step 110) from a light source 11. This stimulating light isdirected to illuminate (step 120) an information bearing target area 13of an image plate 19 where such illumination occurs about the normal 21of an aperture coincident with the a portion of the information bearingtarget area 13.

The information bearing target area 13 responds to the stimulating light1 by emitting information-bearing light 2 of a second sense, such asfluorescing blue light. This information-bearing light is received (step130) about the about the normal 21 of the image aperture 20 centered ona portion of the information bearing target area 13. In addition to theinformation-bearing light 2 being emitted from the target area 13, aportion of the stimulating light 1 is reflected back through the imageaperture 20 as backscatter light 3.

The combined information-bearing light 2 and backscatter light 3 iscollimated (step 140) upon exiting the aperture, for example byreflection from the first parabolic reflector 12. The resultingcollimated combined light 4 is then processed into collimatedinformation bearing light 5 such as by reflection from and transmissionthrough dichroic beam splitters to reject (step 150) backscatter light3. Advantageously, this rejection of backscatter light is performed incollimated space, allowing for the use of very efficient filters.

Finally, the focused information-bearing light 6 is recovered (step 160)from the collimated information bearing light 5 and transferred (step170) to an information receiving target 17, such as by the focusingaction of said second parabolic reflector 16.

An added dimension of flexibility for a confocal scanning system, suchas that illustrated in FIG. 1 above can be obtained through scanning theimage plate using either macro-steps or micro-steps. For example,assuming that the confocal scanner system has just read the informationresiding within a target area on the information bearing target, amacro-step will move the aperture to a new location of a distance atleast as great as the aperture size, while a micro-step will move adistance less than an aperture size. Macro-stepping can be used to veryquickly obtain a gross image. On the other hand, micro-stepping can beused to provide detailed imagery—in the case of computed radiography, anincreased resolution in an area of interest. Macro-stepping andmicro-stepping methodology is similar to what is known in the art ofink-jet printing, such as is described in Hickman (U.S. Pat. No.6,457,806). Such micro-stepping, in combination with a high qualityimage aperture and rapid translation across the information bearingtarget, can also eliminate the need for a line or area charge-coupleddevice (CCD), greatly simplifying the optical complexity and cost, whilestill providing high resolution scanning and throughput.

In applications of the present invention where the information receivingtarget 17 comprises a non-rectangular pixilated array, such as the typeof arrays discussed in Shizukuishi (U.S. Pat. No. 6,717,190), it isdesirable to match the shape of image aperture 20 at the informationbearing target to the shape of the image sensor.

The system can also employ a number of image aperture 20 masks that canbe selected into place to allow various resolution modes, for example,in the case of computed radiography, a finer aperture set can be alsoused to increase the resolution of an area of interest. Also, aplurality or array of confocal systems as taught in the presentinvention can be employed to increase image-scanning throughput.

It should be noted that for an all-reflective confocal scanner, such asshown in FIG. 1, those parabolic reflectors have larger off-axisaberrations than most refractive optical elements. Accordingly, it ispreferred that the information bearing target area 13 be small andlocated centrally on the focal point of first parabolic reflector 12.Similarly, it is preferred that the information receiving target 17 beas small as practical and also be located centrally on the focal pointof second parabolic reflector 16.

Referring now to FIG. 4, which shows a second confocal scannerconfiguration, using certain refractive optical elements, in accordancewith the present invention. Focused stimulating light 1 of a firstsense, such as red light, from a light source 11 passes through a secondaperture 30, in apertured second cold mirror 24, continues through afirst aperture 23, in apertured collimating lens 22, further continuesthrough image aperture 20, and impinges on the information-bearingtarget area 13 on the image plate 19. The information-bearing targetarea 13 responds by emitting information-bearing light 2 combined withback-scatter light 3 where this combination which passes back throughimage aperture 20.

The combination of information-bearing light 2 and backscatter light 3is collimated as it passes through apertured collimating lens 22,forming collimated combined light 4. Collimated combined light 4 strikesapertured second cold mirror 24 where a portion of the backscatter light3 is separated from collimated combined light 4 as collimated combinedlight 4 is reflected from apertured second cold mirror 24 and directedtoward hot mirror 25. Collimated combined light 4 passes through hotmirror 25, where another portion of the backscatter light 3 is removedby being reflected away, such as toward a red-beam dump (not shown).Next, collimated combined light 4 is reflected from first cold mirror 27as collimated information bearing light 5, where substantially allbackscatter light 3 has been removed.

Focused information bearing light 6 is recovered from collimatedinformation bearing light 5 by the focusing action of focusing lens 26,where this focused information-bearing light 6 is directed toinformation receiving target 17.

Refer now to FIGS. 5 and 6, which show a third illustrative confocalscanner configuration embodying my invention. Focused stimulating light1 of a first sense, such as red light, from a light source 11 enters acoated lower prism 31 where it is reflected from a first hot mirrorcoating 32 and passes through the first aperture 23, in aperturedcollimating lens 22. Stimulating light 1 continues through imageaperture 20, and impinges on the information-bearing target area 13 onthe image plate 19. The information-bearing target area 13 responds byemitting information-bearing light 2 combined with backscatter light 3where this combination passes back through image aperture 20.

The combination of information-bearing light 2 and backscatter light 3is collimated as it passes through apertured collimating lens 22,forming collimated combined light 4. Collimated combined light 4 passesinto a coated lower prism 31 where a portion of backscatter light 3 itis reflected away by first hot mirror coating 32, such as toward ared-beam dump (not shown). Collimated combined light 4 then passes intocoated upper prism 41, where another portion of backscatter light isprevented from entering the upper coating prism by second hot mirrorcoating 42.

Collimated combined light 4 continues to pass though coated upper prism41, impinging upon third hot mirror coating 43, which acts to removesubstantially all backscatter light 3 so that the light exiting prism iscollimated information-bearing light 5, which contains substantiallyonly target light. Focused information bearing light 6 is recovered fromcollimated information bearing light 5 by the focusing action offocusing lens 26, where this focused information-bearing light 6 isdirected to information receiving target 17.

Referring finally to FIG. 7 and continuing to refer to FIG. 6, a fourthillustrative confocal scanner configuration, using non-imaging optics,in accordance with my invention is shown.

Stimulating light 1 of a first sense, such as red light, from a lightsource 11 enters a first tapered non-imaging optic 51, where it iscollimated. This collimated stimulating light 1 then enters coated lowerprism 31 where it is reflected from a first hot mirror coating 32 andpasses into a second tapered non-imaging optic 52, where it isreconcentrated. Stimulating light 1 exits from second taperednon-imaging optic 52, continues through image aperture 20, and impingeson the information-bearing target area 13 on the image plate 19. Theinformation-bearing target area 13 responds by emittinginformation-bearing light 2 combined with back-scatter light 3 wherethis combination which passes back through image aperture 20.

The combination of information-bearing light 2 and backscatter light 3is collimated as it passes through second tapered non-imaging optic 52,forming collimated combined light 4. Collimated combined light 4 passesinto a coated lower prism 31 where a portion of backscatter light 3 itis reflected away by first hot mirror coating 32. Collimated combinedlight 4 then passes into coated upper prism 41, where another portion ofbackscatter light is prevented from entering the upper coating prism bysecond hot mirror coating 42.

Collimated combined light 4 continues to pass though coated upper prism41, impinging upon third hot mirror coating 43, which acts to removesubstantially all backscatter light 3 so that the light exiting prism iscollimated information-bearing light 5, which contains substantiallyonly target light. Focused information bearing light 6 is recovered fromcollimated information bearing light 5 by the concentrating action ofthird tapered non-imaging optic 53, where this focusedinformation-bearing light 6 is directed to information receiving target17.

Aperture 20 should be located at the snout end aperture of taperednon-imaging optical element 52 and in close proximity to target area 13.The gap between target area 13 and the snout end aperture should be madeas small as practical to minimize the illuminated target area.

Similarly, the snout end aperture of tapered non-imaging optical element53 should be located in close proximity to information receiving area17. The gap between information receiving area 17 and the snout endaperture should be made as small as practical to minimize theilluminated information receiving area.

The housing clearance holes for the snout apertures of taperednon-imaging optical elements 52 and 53 can be a substrate formed from athin sheet with apertures that match the snout apertures. By bringingthe snout and sheet apertures in alignment with each other and in closeproximity with targets 13 and 17, the resolution and image quality ismaximized.

Alternatively, the holes in the housing adjacent to target area 13 andinformation receiving area 17 can be of a conical shape that matches thesides of tapered non-imaging optical elements 52 and 53. The aperturesize of the conical housing holes can be made to match those of theconical end apertures of tapered non-imaging optical elements 52 and 53.The conical housing holes can engage the conical ends of taperednon-imaging optical elements 52 and 53 thereby providing a means ofsecuring tapered non-imaging optical elements 52 and 53 in place. Toprevent absorption at tapered non-imaging optical element contact areas,reflective film such as, for example, aluminum can be applied either tothe conical end surfaces of tapered non-imaging optical elements 52 and53 or to the conical housing apertures they engage. The same reflectingfilm application method alternatives can be implemented at otherstructural contact areas of tapered non-imaging optical elements 52 and53 and of prisms 31 and 41. These contact areas, needed to secure theseelements in position, should be minimized.

List of Acronyms Used in the Specification

The following is a list of the acronyms used in the specification inalphabetical order.

CCD charge-coupled device LED light emitting diode

ALTERNATE EMBODIMENTS

Alternate embodiments may be devised without departing from the spiritor the scope of the invention. For example, while the embodiments abovedescribe the two light senses as two wavelength bands of light, theinvention can be fashioned to utilize any two senses of electromagneticenergy. In addition, the term “information” as used in “informationbearing” can comprise images, such as in radiography or solid statephotography images, data, the presence of a compound, such as influorescent tagging of DNA or luminescent security features in currency,or the exposure to radiation such as in radiation dosimetry. The term“information receiving” can be a projection screen or surface, the humaneye, photographic film in the case of a projected image, or a photodiodeor CCD in the case of radiography

1. A radiation information recording system comprising: (a) a firsttapered non-imaging optical element configured to accept a light inputand provide a collimated light output; (b) a first prism having first,second, and third surfaces, said first surface of said first prismadjacent said first tapered non-imaging optical element and in opticalcommunication therewith; (c) a second tapered non-imaging opticalelement having a first surface and a second surface distally opposedsaid first surface, said first surface of said second taperednon-imaging optical element being adjacent said second surface of said afirst prism and in optical communication therewith; (d) an imageaperture (20) adjacent said second surface of said second taperednon-imaging optical element and in optical communication therewith; (e)a second prism having first, second, and third surfaces, said firstsurface of said second prism adjacent said third surface of said firstprism and in optical communication therewith; (f) a beam-splitterlocated between said first surface of said second prism adjacent saidthird surface of said first prism; and (g) a third tapered non-imagingoptical element having a first surface and a second surface distallyopposed said first surface, said first surface of said third taperednon-imaging optical element being adjacent said second surface of saidsecond prism and in optical communication therewith.
 2. A method forusing stimulating light (1) to stimulate an information bearing targetarea (13) into releasing information bearing light (2) and transferringsaid information bearing light to an information receiving target (17),wherein said initial stimulating light and said resultantinformation-bearing light do not pass through a common refractiveelement having optical power, said method comprising: (a) receiving(110) stimulating light (1) of a first sense from a light source (11);(b) illuminating (120) said information bearing target area withstimulating light (1), said illumination occurring about the normal (21)of an image aperture (20) coincident with a portion of theinformation-bearing target area; (c) receiving (130) a combination ofinformation bearing light of a second sense emitted from saidinformation bearing target area in response to said illumination andbackscatter light (3) of the first sense reflected from saidinformation-bearing target, (i) said information bearing light being ofa second sense, and (ii) said reception also occurring about the normalof said aperture; (d) collimating (140) the combination of informationbearing light and backscatter light to form a collimated combined light(4); (e) rejecting (150), in collimated space, the backscatter lightportion from said collimated combined light; (f) recovering (160) saidinformation-bearing light; and (e) transferring (170) said informationbearing light to said information receiving target.
 3. The method ofclaim 2 wherein the information receiving target is selected from thegroup consisting of: human eye, projection screen, projection surface,and semiconductor detector array.
 4. The method of claim 2 wherein asource of said stimulation light is selected from the group consistingof: laser, light emitting diode, and short arc lamp.
 5. The method ofclaim 2 wherein said information bearing target area includesinformation selected from the group consisting of: an image, a datapattern, a fluorescent tagged element, a luminescent element, adosimeter.
 6. The method of claim 2 wherein said first and second lightsenses are selected from the group consisting of: wavelength, phase, andpolarization state.
 7. The method of claim 2 wherein the confocaloptical system and an image plate (19) are translated relative to eachother in order to transfer information from more than one informationbearing target area.
 8. The method of claim 2 wherein the rejecting ofsaid backscatter light comprises the use of a plurality of filters basedon the first and second sense of said backscatter light and saidinformation-bearing light.